Nutritional Assessment and Interventions in Elective Hip and Knee Arthroplasty: a Detailed Review and Guide to Management

Abstract

Purpose of Review

8.5 to 50% of total joint arthroplasty (TJA) patients are reported to have preoperative malnutrition. The narrative review identifies the relationship between preoperative malnutrition for TJA patients and postoperative outcomes as well as the use of perioperative nutritional intervention to improve postoperative complications.

Recent Findings

Biochemical/laboratory, anthropometric, and clinical measures have been widely used to identify preoperative nutritional deficiency. Specifically, serum albumin is the most prevalent used marker in TJA because it has been proven to be correlated with protein-energy malnutrition due to the surgical stress response. However, there remains a sustained incidence of preoperative malnutrition in total knee arthroplasty (TKA) and total hip arthroplasty (THA) patients due to a lack of agreement among the available nutritional screening tools and utilization of isolated laboratory, anthropometric, and clinical variables. Previous investigations have also suggested preoperative malnutrition to be a prognostic indicator of complications in general, cardiac, vascular, and orthopaedic surgery specialties.

Summary

Serum albumin, prealbumin, transferrin, and total lymphocyte count (TLC) can be used to identify at-risk patients. It is important to employ these markers in the preoperative setting because malnourished TKA and THA patients have shown to have worse postoperative outcomes including prolonged length, increased reoperation rates, increased infection rates, and increased mortality rates. Although benefits from high-protein and high-anti-inflammatory diets have been exhibited, additional research is needed to confirm the use of perioperative nutritional intervention as an appropriate treatment for preoperative TJA patients.

Introduction

Malnutrition is defined as an inability to achieve metabolic and nutritional requirements [1]. The American Society of Parenteral and Enteral Nutrition (ASPEN) categorizes malnutrition as starvation-related, acute disease-related, or chronic disease-related [2]. Nutritional deficiency is especially problematic in the hospital setting, with 30–50% of all hospitalized patients being identified as malnourished [3]. Preoperative malnutrition has been reported to be as high as 50% in patients undergoing surgical procedures and affects two out of every three patients in major surgeries [4•, 5]. Furthermore, when looking at patients undergoing primary or revision total joint arthroplasty (TJA), 8.5 to 50% of patients are reported to have laboratory markers suggestive of malnutrition [6, 7].

Contemporary literature demonstrates a considerable association between preoperative malnutrition and adverse total joint arthroplasty (TJA) outcomes, including length of stay (LOS), reoperation, readmission, and infection rates [8]. One recent study determined a substantial relationship between nutritional deficiency defined by hypoalbuminemia and increased risk of readmission, infection, general complications, and mortality [9••]. Such association is explained, in part, by the surgical stress response that induces inflammatory, acute-phase, hormonal, and genomic responses [10]. The metabolic activation creates a catabolic state which requires the patient to have adequate nutrition prior to the surgery or else risk detrimental outcomes [8, 11]. In an attempt to mitigate adverse surgical outcomes, organizations including the European Society for Clinical Nutrition and Metabolism [8], American Society of Parenteral Enteral Nutrition [1, 12], and the American Society for Enhanced Recovery with Perioperative Quality Initiative [13] developed various surgical nutritional guidelines. Some of the nutritional screening assessments utilized in the clinical setting include the Nutritional Risk Screening 2002 (NRS-2002), Mini Nutritional Assessment (MNA), Malnutrition Universal Screening Tool (MUST), Malnutrition Screening Tool (MST), and the Subjective Global Assessment (SGA) [14, 15]. However, there is no consensus on which screening tool should be considered the “gold standard,” and the lack of unanimity is often cited as a reason for the sustained incidence of preoperative malnutrition [16•].

Through greater awareness of the nutritional measures, parameters, and perioperative interventions available, orthopaedic surgeons can reduce the burden of adverse outcomes associated with malnutrition in TJA. Therefore, the aim of this review was to (1) identify and describe common measurements of nutritional status; (2) evaluate the relationship between malnutrition and postoperative lower extremity TJA outcomes; (3) evaluate whether the use of perioperative nutritional intervention improves outcomes; and (4) briefly discuss other contributors to adverse outcomes that interplay with malnutrition.

Nutritional Assessment

The standard measures of malnutrition are biochemical/laboratory, anthropometric, and clinical. These measures are widely used preoperatively for various types of surgeries [12].

Biochemical and Laboratory Measures

Serum albumin is the traditional standard biochemical marker for nutritional status. Serum albumin levels have been found to correlate closely with the degree of protein-energy malnutrition and exemplify the relationship between nutritional deficiency and systemic inflammation [4•, 17, 18]. Previous investigations have shown preoperative hypoalbuminemia (<3.5 g/dL) to be a prognostic indicator of increased mortality and negative outcomes in general, cardiac, vascular, and orthopaedic surgery specialties [4•, 17–24]. Although serum albumin is the most widely used biochemical measure, various other biochemical markers such as prealbumin (<10–15 mg/dL), total lymphocyte count (<1500 cells/mm³), transferrin (<200 mg/dL), and hemoglobin (<13 g/dL) are also used (Table 1) [14, 25–28]. It is critical to note the absence of consensus on the reference ranges used to assess nutritional status [14]. However, levels have been consistently reported within specific ranges, and fine-tuning of the indistinctness will provide a better prediction of adverse patient outcomes [25–28].

Table 1.

Criteria for defining malnutrition

Biochemical marker	Value indicating malnutrition
Albumin	<3.5 g/dL
Prealbumin	<10–15 mg/dL
Total lymphocyte count	<1500 cells/mm3
Transferrin	<200 mg/dL
Hemoglobin	<13 g/dL

Similar to albumin, depletion of serum prealbumin demonstrates a relationship between malnutrition and systemic inflammation; however, prealbumin has shown to be a more sensitive marker for acute nutritional status changes due to its shorter half-life [26, 29–31]. One study found a significant reduction in prealbumin with an energy-restricted diet of 20 g (p < 0.01), 40 g (p < 0.05), or 60 g (p < 0.005) protein/day and no significance found for albumin levels [31]. Furthermore, prealbumin is easily quantified on laboratory instruments and is less affected by liver disease than various other serum proteins [27]. Depletion of total lymphocyte count (TLC), transferrin, and hemoglobin are also viable biomarkers for nutritional status [14, 23, 28, 32]. The decrease in TLC seen in patients with malnutrition is not clearly understood; however, it is most likely to be related to thymus atrophy and lack of protein needed to produce lymphocytes [33, 34]. Transferrin is a serum protein that may produce iron-deficiency state inaccuracies as levels are elevated due to an increased amount of iron absorption [25]. Lastly, malnutrition may lead to vitamin B12, folate, or iron deficiency, resulting in low hemoglobin [35]. As with albumin, deficiency in TLC, transferrin, and hemoglobin also produce worse postoperative outcomes measured by LOS, postoperative complications, and mortality [23, 32, 36].

Preoperative malnutrition in Orthopaedic Surgery is most often assessed through biochemical measures [37]. Specifically, serum albumin has been the most widely studied stand-alone biochemical measure which was found to predict malnutrition in orthopaedic patients and correlate to worse postoperative outcomes, including any complications (odds ratio, OR = 1.5; 95% CI, 1.2–1.7), serious complications (OR = 1.4; 95% CI, 1.0–1.9), surgical site infection (OR = 2.0; 95% CI, 1.5–2.8), LOS (OR = 0.20; 95% CI, 0.12–0.27), and unplanned hospital readmission (OR = 1.4; 95% CI, 1.2–1.7) [38]. Several standardized scoring systems have been developed to provide an integrated preoperative nutritional status assessment for orthopaedic patients based on multiple laboratory values. The Rainey-MacDonald nutritional index (RMNI) combines patients’ serum albumin and transferrin levels and has proven to accurately predict postoperative complications (sensitivity = 79.1%) [39, 40]. Conversely, the Prognostic Nutritional Index (PNI) provides a weighted score based on patients’ serum album and TLC levels and has been associated with aseptic wound problems in TJA patients (OR = 0.858; 95% CI, 0.771–0.955; p = 0.015) [41]. The routine use of biochemical parameter-based scoring systems provides a reasonably accurate and readily available indication for underlying malnutrition. However, such scoring systems should be used with caution. Basing nutritional assessment solely on laboratory values may lack the comprehensive assessment of patients’ nutritional history, comorbidities, socioeconomic situation, and anthropometrics required to establish a diagnosis and an underlying cause of malnutrition.

Anthropometric measures

Anthropometric measures of malnutrition include quantitative measurements of the muscle, bone, and adipose tissue to assess body composition [42]. The main elements of anthropometry used in orthopaedics to determine nutritional status include body weight/BMI, mid-upper arm/calf circumference, and triceps skinfold thickness [43].

Low BMI is a commonly accepted criterion for nutritional assessment and is the most frequently utilized anthropometric measure for nutritional assessment [44]. Traditionally, BMI <18.5 kg/m² has been used as an indicator of malnutrition [14, 44–46]; however, several investigations have shown that a cut-off of <20.5 kg/m² (OR = 31.0; 95% CI, 14.21–67.44)[47] or even <22 kg/m² for patients older than 70 years (as defined by European Society of Clinical Nutrition and Metabolism) [44] may provide higher accuracy in assessing nutritional risk. Calf circumference (CC) is used primarily as an anthropometric measurement because a decrease in CC is correlated with loss of subcutaneous fat and muscle mass [48]. The utility of CC can be seen primarily as a screening tool for the elderly, encompassed in the MNA that defines malnutrition as a CC <28.0 cm for males and < 25.0 cm for females [49]. Similarly, mid-upper arm circumference (MUAC) is used for the same reason, though primarily to indicate acute malnutrition in children [50, 51]. The World Health Organization (WHO) recommends using 11.5 cm and 12.5 cm as cut-offs for admission and discharge malnutrition criteria in children under 5 years old, respectively [50]. Reference ranges for adolescents and adults have been variably defined; however, one study found a MUAC of 24.0 cm may be an effective cut-off value to determine malnutrition [51]. MUAC is performed more frequently than CC as a screening tool in hospitalized and preoperative patients due to its ease of use [52–54]. As with the biochemical measures, anthropometric measures have been used to predict postoperative outcomes and are associated with LOS, postoperative complications, and morbidity [4•, 32, 55–57].

CC and MUAC are some of the more commonly used anthropometric measurements in orthopaedics [37]. Additionally, various nutritional screening tools used in orthopaedics have utilized anthropometric measures, including the MNA, which creates a scoring system based on the patient’s BMI [58]. The viability of MNA has been extensively studied and proven to be successful by accurately predicting malnutrition in patients, resulting in an increased mortality rate [59, 60•]. MNA has also shown to be a better predictor of wound healing following hip fracture compared to the Rainey-MacDonald nutritional index mentioned earlier [61].

Clinical measures

Clinical measurements can be defined as a change in physiological function secondary to a lack of adequate nutrition; therefore, they resemble the pathologic sequelae of malnutrition [62]. The nutritional deficiency is usually specific to a particular nutrient. For example, iodine deficiency may be associated with thyroid dysfunction, and vitamin A deficiency may cause visual disorders and compromised night vision [63]. While not directly relevant to the orthopaedic examination, such manifestations should raise suspicion among orthopaedic providers and prompt further evaluation. This is critical, given that clinical measures have been shown to predict malnutrition-associated complications more accurately than several biochemical, anthropometric, or combination of the two markers [64].

The Subjective Global Assessment (SGA) is one such method and evaluates nutrition based on clinical judgment [14, 64–66]. SGA utilizes patient history as well as physical examination findings to classify patients into one of three categories: (A) well-nourished, (B) mildly/moderately malnourished, or (C) severely malnourished [66]. Those in the well-nourished group have no decrease in food/nutrient intake; <5% weight loss; no/minimal symptoms affecting food intake; no deficit in function; and no deficit in fat or muscle mass. Group A patients can also be someone with criteria for SGA group B or C but with recent adequate food intake; non-fluid weight gain; significant recent improvement in symptoms; significant recent improvement in function; and chronic deficit in fat and muscle mass but with recent clinical improvement in function. Mildly/moderately malnourished patients are those with a definite decrease in food/nutrient intake and may or may not have 5–10% weight loss; mild symptoms affecting food intake; moderate functional deficit; or mild to moderate loss of fat/muscle mass. Group B patients can also be those with criteria for SGA C but with improvement in the aforementioned deficits. Lastly, patients in the severely malnourished group have severe deficit in food/nutrient intake; >10% weight loss which is ongoing; significant symptoms affecting food/ nutrient intake; and severe functional deficit OR recent significant deterioration with obvious signs of fat and/or muscle loss.

Relationship between malnutrition and outcomes after TKA and THA

Preoperative hypoalbuminemia exhibits a strong correlation to worse TKA and THA postoperative outcomes, including, but not limited to, prolonged LOS; increased 30-day, 90-day, and 6-month readmission rates; reoperation rates; infection rates; and 30-day and 12-month mortality rates (Table 2). Prealbumin, transferrin, and TLC have been used to measure malnutrition in preoperative TKA and THA patients; however, they have not been as widely utilized as albumin. Since preoperative malnutrition is associated with worse postoperative outcomes, correcting the particular nutritional deficiency prior to surgery may have immense benefits for the patient. The patient will have less postoperative complications resulting in less financial burden as well as an enhanced recovery course.

Table 2.

Summary of the association between malnutrition and adverse outcomes after lower extremity total joint arthroplasty (TJA)

Author	Patient (n)	Biochemical marker	Postoperative measures	Findings
Nelson et al., 2015	77,785 TKA	Albumin	Postoperative infection, postoperative major complications	Malnourished patients had significantly increased prevalence of postoperative infection (p < 0.001) and major complications which included mortality (p = 0.050).
Roche et al., 2018	16,1625 TKA	Albumin, prealbumin, transferrin	Wound complications, infections, CoIW, infection followed by wound complications	Malnourished patients had significantly higher wound complications (OR: albumin = 2.3, OR: prealbumin = 1.9, OR: transferrin = 1.9), infections (OR: albumin = 2.2, OR: prealbumin = 1.87, OR: transferrin = 1.87), CoIW (OR: albumin = 2.9, OR: prealbumin = 2.27, OR: transferrin = 1.79), and infection followed by wound complications (OR: albumin = 2.87, OR: prealbumin = 2.22, OR: transferrin = 1.78).
Ryan et al., 2018	128,412 total 79,661 TKA 48,751 THA	Albumin	Postoperative complications including infection, readmission, reoperation and death	Malnourished patients had significantly increased postoperative complication rates including death, superficial infection, pneumonia, reintubation, transfusion, readmission, and reoperation (p < 0.05).
Black et al., 2019	4047 total 2058 TKA 1989 THA	Albumin	90-day readmission, 90-day ED visit, LOS, discharge to SNF/rehab	Malnourished patients had significantly longer LOS (p < 0.0001); higher 90-day readmission (OR = 1.55; 95% CI, 1.26–1.92), 90-day ED visit rates (OR = 1.35; 95% CI, 1.14–1.59), and were more likely to be discharged to SNF/rehab (p < 0.0001).
Newman et al., 2020	1667 THA	Albumin	LOS, postoperative complications, reoperation rates	Malnourished patients had significantly longer LOS (p < 0.0001), 80% higher risk for any complication (OR = 1.80; 95% CI, 1.43–2.26) 113% higher risk for major complications (OR = 2.13; 95% CI, 1.31–3.48), 79% higher risk for minor complications (OR = 1.79; 95% CI, 1.42–2.26) and 97% increased risk for reoperation (OR = 1.97; 95% CI, 1.20–3.23).
Kishawi et al., 2020	n = 125,162 primary TJA 57% TKA (n = 71,342) 39% THA (n = 48,813) n = 9,846 revision TJA 46% rTHA (n = 4529) 52% rTKA (n = 5120)	Albumin	Postoperative complications including return to operating room and infection	Upper and lower extremity TJA data were combined showing patients with hypoalbuminemia had significantly higher postoperative complications including return to operating room, deep and superficial surgical site infections (p < 0.0001). No significance found for DVT (p = 0.4807), PE (p = 0.4676) or wound disruption (p = 0.5590).
Eminovic et al., 2021	220 THA	Albumin, TLC	LOS, postoperative complications	Preoperative LOS was significantly longer for malnourished patients (p < 0.001); however, postoperative LOS did not show a significant difference (p < 0.544). Malnourished patients had a significantly higher rate of postoperative complications which included infection and unforeseen readmissions (p < 0.001).
Johnson et al., 2021	84,315 TKA	Albumin	30-day readmission, Infection, postoperative complications, and mortality	Malnourished patients had 3.8 (95% CI, 3.0–4.7) times increased odds of infection, 2.3 (95% CI, 2.0–2.7) times higher odds of readmission, 3.7 (95% CI, 3.3–4.1) times higher odds of all-cause complications, and 7.2 (95% CI, 4.5–11.6) times higher odds of mortality.

TKA total knee arthroplasty, THA total hip arthroplasty, CoIW concomitant infection with wound, ED emergency department, LOS length of stay, SNF skilled nursing facility, DVT deep vein thrombosis, PE pulmonary embolism, TLC total lymphocyte count, BMI body mass index

Current literature supports a relationship between preoperative malnutrition and postoperative complications after TJA. Of the eight analyzed studies, six used albumin only to identify preoperative malnutrition, one used TLC combined with albumin, and one used albumin, prealbumin, and transferrin separately [9, 24, 36, 67•, 68, 69, 70••, 71]. A detailed description of the literature reported findings is presented in Table 2. There was consensus among all included studies affirming the association between preoperative malnutrition and increased risk of adverse postoperative outcomes. Post-TJA malnutrition-related complications included 30-day, 90-day, and 6-month infection rates, cardiac arrest, pneumonia, readmission rates, reoperation rates, ED visit rates, and discharge rates to a skilled nursing facility (SNF)/rehabilitation center as well as 30-day and 12-month mortality. Furthermore, two studies reported a correlation between nutritional deficiency and increased LOS, yet Eminovic et al. only found a correlation with preoperative LOS and not postoperative LOS [67•, 70••, 71].

Hypoalbuminemia studies

In a retrospective study by Kishawi et al. [69], the authors analyzed the effects of hypoalbuminemia (<3.5 g/dL) on various 30-day postoperative complications for upper and lower extremity TJA patients. Of the 135,008 patients included in the study, 125,162 had undergone primary arthroplasty, with 57% (n ~ 71,342) involving the knee and 39% (n ~ 48,813) of the hip. Multivariate regression analysis determined an association between hypoalbuminemia and postoperative outcomes, including organ or space surgical site infection (OR = 2.65; 95% CI, 1.88–3.75), superficial incisional surgical site infection (OR = 1.70; 95% CI, 1.33–2.17), deep incisional surgical site infection (OR = 2.53; 95% CI, 1.82–3.53), wound infection (OR = 4.25; 95% CI, 3.59–5.05), return to operating room (OR = 1.74; 95% CI, 1.51–2.00), and unplanned intubation (OR = 3.23; 95% CI, 2.46–4.25). Black et al. [70••] conducted a retrospective study of 2058 TKA and 1989 THA patients, showing a relationship between hypoalbuminemia and postoperative complications. Using a multivariable model controlling for a variety of demographic factors and comorbidities, the study concluded that malnourished patients had increased risk for 90-day readmission (OR = 1.55; 95% CI, 1.26–1.92) and 90-day ED visits (OR = 1.35; 95% CI, 1.14–1.59). Limitations of the study included 6108 (60.1%) of the primary TKA/THA patients excluded from data analysis due to missing preoperative albumin values. Johnson et al. included 84,315 TKA patients categorized as optimized (BMI <40 kg/m², albumin >3.5 g/dL, nonsmokers, and nondiabetic) or non-optimized and also grouped based on the four previously mentioned risk factors [9]. A multivariable logistic regression model was used to determine the effect of each modifiable risk factor on the risk of postoperative infection, readmission, any complication, and mortality. Patients with hypoalbuminemia had increased odds of infection (OR = 3.8; 95% CI, 3.0–4.7), readmission (OR = 2.3; 95% CI, 2.0–2.7), any complication (OR = 3.7; 95% CI, 3.3–4.1), and mortality (OR = 7.2; 95% CI, 4.5–11.6).

Interventions for malnutrition can improve outcomes

Nutritional supplementation may be one solution for mitigating poor postoperative outcomes. Nutritional support, including dietary advice, oral nutritional supplementation, or enteral and parenteral nutrition, for hospitalized patients has shown mixed results. Some meta-analyses have shown that nutritional support has no significant effect on mortality at discharge/4–6-month follow-up (OR = 0.96; 95% CI, 0.72–1.27) [72] or on short-term serious adverse events at a mean of 10.4 days after intervention (risk ratio, RR = 0.93; 95% CI, 0.86–1.01) [73]. Conversely, a more recent meta-analysis determined patients receiving nutritional support did have a significant reduction in mortality (OR = 0.73; 95% CI, 0.56–0.97) [74]. Furthermore, a population-based cohort study of 114,264 hospitalized patients showed an association between nutritional support and a reduction in all-cause inpatient mortality rate and 30-day readmission rates [75•]. Multiple randomized controlled trials, one utilizing a high-protein, energy dense nutritional supplement, and the other utilizing protocol guided nutritional support, showed similar promising results with the treatment group having a significantly lower mortality rate than the control group (p < 0.05) [76, 77]. Furthermore, the use of nutritional supplementation has shown to be advantageous for patients prior to undergoing various procedures including abdominal surgery [77].

Preoperative nutritional intervention for TJA patients has been less widely studied; however, as shown in Table 3, it has shown to provide postoperative benefits and should be considered for further investigation. The literature that is available utilizes either some form of carbohydrate solution or protein-dominant diet to study their effects on LOS and postoperative complications or outcomes [78–81]. The carbohydrate solution-based interventions have mixed results, with Alito and De Aguilar-Nascim reporting no significance for LOS and Harsten et al. determining that LOS was significantly improved (p < .01) [78, 80]. Protein supplementation significantly improved postoperative complications (p = 0.003) [79] as well as charges incurred by the patient for services (p < 0.001) [81••] in two separate studies. The specific charges that were studied included primary hospitalization charges, charges associated with hospital readmissions, and 90-day total charges.

Table 3.

Summary of the use of nutritional supplementation to improve postoperative outcomes

Author	Design	Patient (n)	Intervention	Postop measures	Findings
Alito and De Aguilar-Nascimento, 2016	RCT	32 THAs	400 ml of oral 12.5% carbohydrate solution 1.5 h before and 2 h after surgery	Six different pain and discomfort parameters; LOS	Treatment group had less pain at 12, 16, and 20 h postop (median scores 20, 30, and 34 vs. 7, 5, and 0 mm; p < 0.05) compared to control group. No significant difference was found between groups for LOS
Botella-Carretero et al., 2010	RCT	60 THAs	52.2 ± 12.1% energy–protein supplements (40 g of protein and 400 kcal per day) per day for 5.8 ± 1.8 days before surgery and until discharge	Serum proteins, BMI, postoperative complications	Treatment group had significantly higher albumin (p = 0.002) and prealbumin (p = 0.045) postop compared to control group. Only supplemented proteins per day (OR = 0.925; 95% CI, 0.869–0.985) were associated with less postoperative complications (p = 0.003).
Harsten et al., 2012	RCT	60 THAs	ACERTO protocol (6 h preoperative fasting for solids, 200 mL of 12.5% maltodextrin up to 2 h before surgery, restricted IV fluids and preoperative immune nutrition for 5 days prior to surgery)	LOS, postop C reactive protein	Treatment group (median = 3 days, range 2–5 days) stayed a median of 3 days less (p < 0.01) than the control group (median = 6 days, range 3–8 days).
Schroer et al., 2019	Longitudinal Cohort Study	4733 THAs and TKAs (number of each not specified)	Nutritional intervention program encouraging a high-protein, high anti-inflammatory food diet beginning prior to surgery and continuing for at least 1-month post-surgery	LOS, readmission, charges incurred by the patient for services	Nutritional supplementation for the malnourished cohort at the study hospital only showed significance for charges incurred (p < 0.001).

TKA total knee arthroplasty, THA total hip arthroplasty, RCT randomized control trial, LOS length of stay, BMI body mass index, ACERTO ACEleração da Recuperação TOtal Pós-operatória

Schroer et al. describes the use of a postoperative nutritional intervention program for patients who had undergone elective TJA and determined to have preoperative malnutrition, as defined by an albumin level of ≤3.4 g/l, showed promising results [81••]. The five-adult hospital network applied a nutritional intervention program centered around the use of high-protein and anti-inflammatory foods that patients were instructed to begin prior to surgery and continue for at least 1-month post-surgery. The results of the study showed that hospital charges related to initial hospitalization, readmissions, and total 90 days of care were significantly decreased for malnourished patients at the study hospital compared to the control hospital (p < 0.001). Botella-Carretero et al. examined the use of oral nutritional supplements consisting of 40 g of protein and 400 kcal per day in a randomized controlled clinical trial [79]. The intervention group had a better postoperative recovery of plasma proteins (p = 0.045) as well as a smaller decrease in serum albumin levels (p = 0.002) when compared to the control group. Furthermore, patients in the intervention group with increased amounts of protein intake per day showed a decreased postoperative complication rate when compared to patients in the control group (OR = 0.925; 95% CI, 0.869–0.985). Conversely, no significant difference was found between the intervention group and control group when comparing LOS, BMI, tricipital fold, or mid-brachial circumference.

Other Contributors to Outcomes Beyond Malnutrition

When discussing the effect of malnutrition on patient outcomes after undergoing TJA, it is important to also mention the other contributors to outcomes that may interplay with nutritional assessment. The frailty of a patient is one factor that has shown to enhance postoperative complications when combined with preoperative malnutrition [82, 83•]. In one retrospective cohort study, 105,997 patients undergoing THA were identified using the American College of Surgeons-National Surgery Quality Improvement Program database, and categorized into groups as either healthy, frail-only, hypoalbuminemia-only, or hypoalbuminemia and frail [82]. Preoperative hypoalbuminemia was defined as a serum albumin level < 3.5 g/dL, and a score of ≥2 on a 5-item modified frailty index score was used to define the frailty of a patient. The study concluded that, when compared to all other groups, patients with preoperative malnutrition defined as hypoalbuminemia combined with frailty at the time of surgery had greater complication rates. Furthermore, patients with combined hypoalbuminemia and frailty had a 30-day mortality rate of 1.9%, significantly higher than the healthy cohort (OR = 12.66; 95% CI, 7.81–20.83). The literature regarding TKA has produced similar results, underlying the importance of frailty and the interaction it has with malnutrition [83•, 84].

Social support is another commonly overlooked factor that has substantial effects on TJA outcomes. Marital status, housing status, tangible support, emotional support, and having a family member or friend to provide support throughout the surgical process can all influence postoperative outcomes such as LOS, physical function, and reported pain [85–87]. An analysis of 1722 observations across 4 hospitals using the modified Groningen Orthopedic Social Support Scale showed TJA patients with very high social support had shorter LOS (p < .05), were more likely to be discharged postoperatively on day 5 (95.6% vs 57.1% in low support group, p < .0001), and more confident to go home at discharge (81.5% vs 33.3% in low support group, p < .0001) [85]. Furthermore, the presence of a friend or family member during the preoperative classes, in the preoperative holding area, and during the last physical therapy session resulted in improved outcome measures.

In addition to frailty and social support, some other factors that may interact with malnutrition include smoking, opioid use, and chronic illnesses such as diabetes mellitus. Smoking is a modifiable preoperative risk factor that has been extensively studied and proven to increase the prevalence of medical complications following TJA [88–90]. Similarly, multiple studies have found an association between preoperative opioid use and enhanced risk of poor postoperative outcomes [91–93]. Diabetes mellitus, specifically inadequate glycemic control prior to surgery, has shown mixed results with some studies showing increased risk of postoperative complications [94, 95] and some studies showing no association [96].

Conclusion

Preoperative malnutrition, defined primarily by hypoalbuminemia, remains highly prevalent despite the recent development of various nutritional guidelines and assessments. Recent research has shown some improvement in TJA malnutrition [97]; however, the lack of consensus regarding measures of nutrition has caused sustained prevalence of nutritional deficiency in the hospital setting [3, 4•, 5–7, 16•]. It is important to neutralize nutritional deficiency for patients undergoing TJA, specifically, because of the increased risk of postoperative complications including increased LOS, infection rate, readmission rate, reoperation rate, and mortality [24, 36, 67•, 68, 69, 70••, 71]. The literature to date on the use of preoperative nutritional supplementation, such as high-protein and high-anti-inflammatory diets, shows promising results to reduce some of the complications resulting from malnutrition [78–80, 81••]. Furthermore, in order to adequately treat the patient, frailty and social support should also be considered as they may interplay with malnutrition. Although additional research is needed to verify the utility of nutritional support in mitigating adverse surgical outcomes in TJA patients, the severity of this issue needs to be urgently addressed among orthopaedic surgeons.

Author Contributions

The conceptualization and idea for the article came from MH, MD and NSP, MD. The literature search and data analysis were performed by MDD, BS. The first draft of the manuscript was written by MDD, BS and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Funding

No funding was received to assist with the preparation of this manuscript.

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Human and Animal Rights and Informed Consent

This article does not contain any studies with human or animal subjects performed by any of the authors.

Conflict of interest

The authors declare that they have no conflict of interest.